how to fix the P0420 code on my Toyota Camry Eighth Generation (2018-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, wrench, torque wrench
• Remove the upstream (pre-catalytic) oxygen sensor:
  1. Locate the upstream oxygen sensor on the exhaust manifold.
  2. Use the O2 sensor socket to unscrew and remove the sensor.
• Install the new sensor:
  1. Apply anti-seize compound to the threads of the new sensor.
  2. Hand-tighten the new sensor, then torque it to the manufacturer’s specifications (typically around 30 Nm).
• Repeat for the downstream (post-catalytic) oxygen sensor if it has also failed.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, exhaust hanger removal tool, torque wrench
• Remove the catalytic converter:
  1. Locate the catalytic converter in the exhaust system.
  2. Remove any exhaust hangers using the exhaust hanger removal tool.
  3. Unbolt the catalytic converter from the exhaust pipe and manifold.
• Install the new catalytic converter:
  1. Position the new catalytic converter in place.
  2. Bolt it securely to the exhaust manifold and pipe, tightening to specifications (typically 40 Nm).
  3. Reinstall the exhaust hangers.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.